trvs on 1 pipesystem Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[kevarch]

hello
any help with the following problem would be greatly appreciated.
i recently had a new combi boiler installed and tvrs fitted to existing radiators, except the bathroom, on a one pipe system.
despite bleeding and balancing the bathroom rad is the only one that gets properly hot. the rest are hot at the top but very cool at the bottom.
i am wondering if the tvrs are causing this and if so would the best option be to remove all tvrs or replace with the wider bore ones which i believe are made specifically for a 1 pipe system
thanks in advance

[ALDA]

To prove it is trv’s : -

Try removing trv adjustment heads from all rad valves.

If rads get hot then you know the trv’s are the root of the problem.

If so, are they fitted to the flow pipe or return? (Most trv’s are fitted to the flow pipe).

Are the rads sludged up?
If so, remove rads and take outside and hose out sludge, then refit.

[kevarch]

Alda
Many thanks for your reply.
I don't think the rads are sludged up as i didn't have this problem with the old system (back boiler) and the installer drained the system and pumped water round until the water ran clear.
Some of the trvs are fitted to the return but i didn't think this mattered with bi-directional type.
would you mind explaining to me how i remove the adjustment heads?

[ALDA]

Kevarch,

Take a look at a trv,

The adjustment head is the wheel you turn to set room temperature that you wish to maintain.

Slightly below this there may be a Knurled Securing Ring Nut, which you can undo by hand.

This allows removal of head from body of valve, which allows valve to remain fully open all the time.

By the way, when your installer commissioned your boiler, he should have made sure that the rads were all heating satisfactorily.
So have the rads ever heated?
If they did heat up, I still think your first step should be to look for sludge in rads before you switch to new trv’s.

ALDA

[kevarch]

alda
thanks again for your reply
the rads did heat up on the previous system so i will take one off and check for sludge and if it is clear i'll try removing the head on one of the trvs.
the installer has what i would call a'casual' approach to his aftercare so i am trying to find out the exact problem and then call him back to rectify the problem(s)